消除全空域效应:原理、装置与应用实例

如何消除"全空域效应"是电磁勘探中的难题,国内外学者试图从基础理论、数据处理、测线布设等方面入手来解决,但存在求解条件苛刻、计算繁杂、技术实现困难、成本高等问题.文中提出了用屏蔽装置直接消除全空域效应以逼近地面式测量的新思路,研制了相应的装置,给出了使用方法和应用实例,取得了良好的实践效果.     

Impact of climate change on runoff and uncertainty analysis

Natural Hazards - It is necessary to analyze the future runoff changes using a more realistic climate classification scheme. This paper investigates the climate changes and runoff variation by...     

Sequestration of CO2 in geological media: Criteria and approach for site selection in response to climate change

The well-developed coal electricity generation and coal chemical industries have led to huge carbon dioxide (CO₂) emissions in the northeastern Ordos Basin. The geological storage of CO₂ in saline aquifers is an effective backup way to achieve carbon neutrality. In this case, the potential of saline aquifers for CO₂ storage serves as a critical basis for subsequent geological storage project. This study calculated the technical control capacities of CO₂ of the saline aquifers in the fifth member of the Shiqianfeng Formation (the Qian-5 member) based on the statistical analysis of the logging and the drilling and core data from more than 200 wells in the northeastern Ordos Basin, as well as the sedimentary facies, formation lithology, and saline aquifer development patterns of the Qian-5 member. The results show that (1) the reservoirs of saline aquifers in the Qian-5 member, which comprise distributary channel sand bodies of deltaic plains, feature low porosities and permeabilities; (2) The study area hosts three NNE-directed saline aquifer zones, where saline aquifers generally have a single-layer thickness of 3‒8 m and a cumulative thickness of 8‒24 m; (3) The saline aquifers of the Qian-5 member have a total technical control capacity of CO₂ of 119.25 × 10⁶ t. With the largest scale and the highest technical control capacity (accounting for 61% of the total technical control capacity), the Jinjie-Yulin saline aquifer zone is an important prospect area for the geological storage of CO₂ in the saline aquifers of the Qian-5 member in the study area.     

Modeling fluvial response to in‐stream woody vegetation: implications for stream corridor restoration

River restoration and bank stabilization programs often use vegetation for improving stream corridor habitat, aesthetic and function. Yet no study has examined the use of managed vegetation plantings to transform a straight, degraded stream corridor into an ecologically functional meandering channel. Experimental data collected using a distorted Froude‐scaled flume analysis show that channel expansion and widening, thalweg meandering and riffle and pool development are possible using discrete plantings of rigid, emergent vegetation, and the magnitudes of these adjustments depend on the shape of the vegetation zone and the density of the vegetation. These experimental results were verified and validated using a recently developed numerical model, and model output was then used to discuss mechanistically how rivers respond to the introduction of in‐stream woody vegetation. Finally, a hybrid method of meander design is proposed herein where managed vegetation plantings are used to trigger or force the desired morphologic response, transforming a straight, degraded reach into a more functional meandering corridor. It is envisioned that such numerical models could become the primary tool for designing future stream restoration programs involving vegetation and assessing the long‐term stability of such activities. Copyright © 2007 John Wiley & Sons, Ltd.     

Q estimation based on logarithmic spectral areas with different high and low frequencies

When a seismic wave propagates through subsurface viscoelastic media, the formation absorbs the high-frequency energy of the seismic wave more strongly than the...     

EXPERIMENTAL STUDY ON FALL VELOCITY OF NON-UNIFORM SEDIMENT IN FLOWING WATER

I INTRODUCTIONThe settlement of particles in fluid has been studied in many fields such as hydraulics, metallurgy andchemistry since the middle of 19 century because of its great importance. Although the settlement ofsingle particle and group settling velocity of uniform particles in still water are relatively well-studied, yetthe settlement of non-uniform particles in flowing water lacks understanding. For instance, Cunningham(1910), Richardson (1954) and Batchelor (1972), have obtained…     

Epicenter and magnitude of large earthquake determined from high-rate GPS observations: A case study of the 2008 M8.0 Wenchuan earthquake

For earthquake and tsunami early warning and emergency response,the earthquake epicenter and magnitude should be determined rapidly and correctly.Using high-rate GPS observations,we can readily obtain precise and high resolution displacement time series and the seismic waveforms during the earthquake.In this paper,a new algorithm is proposed for estimating the earthquake epicenter and magnitude with the seismic waveforms derived from high-rate GPS data during the earthquake.A case study of the 2008 Wenchuan earthquake is conducted from 1 Hz GPS data and the epicenter and magnitude are determined.Compared with the results issued by the China Seismological Bureau,the estimation error of the epicenter and the magnitude is about 12 km and 0.1 magnitude unit,respectively.It has shown that high-rate GPS could be a new tool feasible for estimating the earthquake epicenter and magnitude,independent of or combined with seismometers.     

我国省域工业主导产业的遴选与发展

工业主导产业在国民经济发展中起着决定性和指向性的作用。主导产业的选择是经济发展阶段的重要课题。依据6个量化指标,从4个维度对"十一五"期间主导产业进行遴选,发现以能源及相关产业为代表的重化工业是各省的重点,高新技术产业成为主导产业的省份较少,劳动密集型产业依然是东部发达省市的重点,预期中的产业转移并未实现;以行业为变量对各省份的主导产业进行聚类分析,可将31个省份划分为5类,反映了我国各省份主导产业布局特点;在此基础上,依据产业生命周期理论和各地区"十二五"发展趋势,提出了相应的对策建议。     

我国港口城市的功能模式研究

基于港口城市功能的评价指标体系,采用主成分分析法,提取反映港口城市功能特征的4个主成分因子;运用分层聚类法对我国21个港口城市的主成分得分进行聚类分析;结合港口功能、城市功能、港口与城市关系等指标对我国港口城市功能模式进行总结,并分析不同功能模式港口城市的发展特征和存在问题;基于港口城市功能模式差异性分析,提出我国港口城市发展的几点建议。     

评<青藏高原晚新生代隆升与环境变化>

由施雅风、李吉均、李炳元先生主编的<青藏高原晚新生代隆升与环境变化>一书,由广东科技出版社正式出版了.这本书总结了"八五"攀登项目"青藏高原形成演变、环境变迁与生态系统研究"的第二课题的研究成果,为青藏高原乃至全球环境演化的研究做出了积极的贡献.